I think when there's overblown criticism (does not take into account the positive things, seeks only to paint in a negative light), that's pretty clearly FUD.
Moreover, when there's a pattern of it occurring, for at least the past 5 years...
Not saying that firefox is perfect, I have issues with its project leadership too, but its nowhere near as bad as the (most vocal) critics like to claim.
If you don't have something to contribute (like a direction, suggestion, correction), then as they used to say, you are "part of the problem".